Multiplex Social Ties andPublic HealthMultiplex social ties are a class of social relationships formed via engagement in multiple social roles, events, groups, and organizations. I seek a deep understanding of why humans need multiplex social ties and the structure and function of interrelated layers of social networks with a focus on their consequences in public health and social norms.

Unethical Behaviors in Network Experiments​Why do people lie and collude, and what are the social conditions that aid such unethical behaviors? With an innovative experiment platform, breadboard, I am conducting a research project that examines unethical behaviors using workers (and their networks) from a large international corporation.

Lifestyle Politics and Political PolarizationWhy is political opinion polarized? Why are seemingly apolitical issues associated with politics? With mixed methods of computer simulation and analysis of large-scale social media data, I demonstrate the wide breadth of political polarization in the U.S. and the possible social mechanisms that could amplify small bias inherent in people's preference.​

Feng Shi*, Yongren Shi*, Fedor Dokshin, Michael W. Macy and James Evans. “Millions of Online Book Co-purchases Reveal Partisan Differences in the Consumption of Science.” Nature Human Behavior (* co-first authors with equal contribution.) [link] (Drop me an email for a copy of the paper. Few institutions have subscribed to this journal. )

Organizational Strategy and Membership DynamicsIs greedy organization that take up all their members' time a viable strategy for membership growth? Why do social media enabled social movements rise in days, but decline in a even faster pace? I explain membership dynamics in two simple yet often-neglected dimensions, time and social network constraints. ​

Respondent-Driven Sampling Respondent driven sampling is a link-tracing sampling method that is able to reach hidden populations, such as MSM, injection drug users and homeless. In this project, we examined one of the important biases in RDS, namely differential recruitment, i.e., respondents with certain characteristics recruit more effectively than others. ​

Familiar Strangers​Strangers are those whom we encounter on a daily basis, yet with whom an intimate social relationship hasn't been established. They are connected with us by social relationships that are weaker than weak ties. How are we influenced by strangers? Do social influence transcend intimate social relationship? ​

Suh, Chan, Yongren Shi and Matthew Brashears. “Negligible Connections? The Role of Familiar Others in the Diffusion of Smoking among Adolescents.” Social Forces: forthcoming.